Backpack and components therefor

ABSTRACT

A backpack having a shoulder harness ( 14 ) and a hip harness ( 20 ). The shoulder harness preferably consists of a pair of padded shoulder strap assemblies ( 14   a  and  14   b ) that have elongate pockets ( 27 ) sewn into their outer linings into which contour plates ( 26 ) are fitted to control the lateral curvature of the straps. The plates are selected to have the stiffness and shape to suit the chest and shoulder shape of the individual user. The hip harness ( 20 ) is preferably divided into independent left and right halves ( 20   a  and  20   b ) that are each pivotally attached to a frame element within the front lower portion of the pack. While the hip harness may be unitary, or the two halves may be more or less tightly coupled together, pivotal attachment of the back of the harness to the pack is highly desirable.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Australian provisional patent application serial number 2003906034, filed Nov. 3, 2003.

TECHNICAL FIELD

This invention relates to backpacks and to backpack shoulder harnesses and hip harnesses.

As a matter of convention, the terms ‘front’ and ‘back’, ‘left’ and ‘right’ and ‘lumbar portion’ when used with a backpack have reference to a standing person wearing the pack. Thus, the front of a backpack is the face that lies adjacent the back of the person and the back of the backpack is the part that is most remote from the person when the pack is worn. Similarly, the right and left sides of the pack are those which lie to the right and left of the person wearing the pack, and the lumbar portion of the pack is the lower portion opposed to the lumbar spine of the user at about the level of the hip harness of the backpack.

BACKGROUND TO THE INVENTION

The backpacks with which this invention is concerned are intended for carrying loads on or against the backs of people. They mostly have some form of load-bearing or distributing frame element, a shoulder harness for supporting some of the load on the shoulders of the user and a hip harness for supporting the remainder of the load on the gluteal muscles and/or hips of the user. The frame element may be incorporated in or otherwise attached to a load bag, or it may be used to support a load directly without the mediation of a load bag. It can be omitted altogether, as in light day-packs where the hip and shoulder harnesses are simply attached to the front of the load bag. When present, the frame element can take many different forms. In light packs it can simply be a cloth stiffening panel sewn into the lower front face of a load bag. With heavy packs, a skeletal metal or plastic frame can be employed that extends the full height of the pack—from the lumbar region of the wearer to shoulder level—with the hip and shoulder harnesses securely attached to it. Smaller metal or plastic frame elements are often fitted into pockets in the front of the load bag with the harnesses secured through to the frame. Or, in the absence of a load bag, the frame can be an external framework to which a load such as a box or drum can be directly secured and to which the shoulder and hip harnesses are also directly attached.

Because of the wide variety of human body shapes and sizes and the wide variety of body movements during walking, climbing, skiing etc, it is difficult to design a back pack—especially one intended to carry substantial loads—to suit a wide variety of people, despite providing adjustable shoulder and hip harnesses. Tailor-making a pack, hip harness, shoulder harness and frame elements to suit an individual is generally impractical for cost reasons. There is therefore a need for a backpack that is better adaptable to a variety of body sizes and walking styles, particularly where substantial loads are carried.

It is my experience that good harness conformance with the shape and walking motions of the wearer is the primary requirement for backpacks, especially when carrying heavy loads. Padding design and fabric choice are secondary considerations.

SUMMARY OF THE INVENTION

From one aspect, this invention involves a backpack in which the hip harness is attached by a pivot joint that permits the harness to rock from side to side with the movement of the user's hips when walking. The hip harness may include separate left and right side segments that are pivotally attached to the pack so that they can move independently of the other. Preferably, the harness is attached to one or more frame elements incorporated in the backpack and, where independently movable segments are employed it is preferred that they are pivotally attached to a common frame element to rotate about separate axes. The separate axes preferably extend substantially horizontally and parallel in the front-to-back direction, one on either side of the spine in the lumbar area of a user wearing the pack.

The backpack preferably includes a primary and substantially inextensible frame element in the lumbar region at the level of the hip harness and, where separate hip harness segments of the type indicated above are used, it is preferable that each segment includes a substantially inextensible hip-plate having front and rear portions. The rear portion of each hip-plate is preferably relatively large and pivotally attached to the primary frame element so that it can overlie the respective gluteus maximus muscle of the user. The front portion of each hip-plate is preferably attached to waist strap and buckle means by which the hip-plates can be coupled together about the waist or the user. Each hip segment preferably includes a padded boot or hip pad that is preferably fitted over the respective hip-plate so as to be interposed between the hip-plate and the body of the user. To mitigate chafing, the edges of the hip-plates may be covered with edging material.

Preferably, the hip-plate of each segment is encased in a tightly fitting cover or pocket of textile fabric having good tensile strength. This helps to reinforce the plate against tearing along stitch-lines, cracking from the periphery and buckling or crumpling under stress. The hip harness buckle means can be attached directly to the hip-plates or to their pockets, allowing the hip harness to be tightened as much as desired without stretch or creep. Resistance to stretch and creep is further enhanced by the pivotal mounting of the hip-plates on the frame element.

The use of independently pivoting side segments allows each side of the hip harness to automatically assume the contour of the wearer's hip region and to move more freely and independently as the pelvis of the walker rocks cyclically during walking or tilts during climbing. It also allows the hip harness to be stowed during storage or transport of the backpack by swinging the side segments upwards against the front of the pack. A zip-around cover flap may be attached to the bottom of the pack, or accommodated within a pocket in the bottom of the load bag, so that it can be pulled out over the stowed hip and shoulder harnesses and zipped in place for transport. This is especially valuable when backpacks are entrusted to the baggage handling systems of airports.

According to an optional feature, where hip-plates of separate hip harness side segments are pivotally attached to the frame element for movement about laterally spaced axes, the rear portions of the hip-plates may be coupled together below the level of their respective pivot axes by a stabilizing strap to limit simultaneous upward movement of the front portions of the hip-plates when the pack is worn. The stabilizing strap may be of adjustable length so that the wearer can adjust the way in which the load is shared by the side segments as the hips move during walking. Of course, some means of undoing the stabilizing strap is necessary to allow the hip side segments to be rotated to their substantially vertical stowage positions.

One way of effecting the pivotal joint by which a side segment is attached to the primary frame element is to mount a threaded metal nut or socket on or in the frame at the desired location, to press a metal eyelet into the respective hip-plate and to enter a screw through the eyelet into the nut or socket to pivotally secure the hip-plate and segment to the frame element. It is envisaged that the screw or nut may rotate with the hip-plate in an eyelet or bore formed in the frame element. While lose-riveting the stiffening plate to the primary frame element (so as to allow pivotal movement) is also envisaged, it makes replacement of the hip-plate and segment more difficult. It will be appreciated, however, that the means by which each hip-plate is attached to the frame is not of prime importance, so long as a pivotal joint is effected.

As already indicated, replaceable padded boot-like covers—here called hip pads—may be fitted over the hip-plates. The length and shape of the hip pads can be chosen to suit the size and shape of the user. The pads can be readily fitted and replaced if desired. The lateral contour of the hip pad will be determined in large part by the lateral contour of the associated hip-plate. The use of the hip-plate and/or its aforementioned pocket to take the tension of the hip harness enables the hip pad to be designed solely for padding and comfort having regard to the intended use of the pack. For example, the carrying of heavy, medium or light loads, bush-walking, alpine ascent and descent, travel in city areas, or day walking.

From another aspect, the invention comprises a backpack having a shoulder harness including left and right shoulder straps that extend over the shoulders of the user and characterized in that a pocket is formed in the top face of each shoulder strap in the shoulder region and a removable flexible contour plate is fitted into each pocket to shape the respective strap in the lateral (generally horizontal direction). Each shoulder strap is formed with inner or lower padding and with an outer or upper lining and the pocket is formed on or in the upper lining. A series of alternative contour plates of different shapes can be fitted into the pocket to force the strap into different lateral configurations, depending upon the slope and contour of the user's neck and shoulders. The contour plate additionally serves to mitigate bunching or edge-curling of the shoulder strap padding over the shoulder.

The plates of the hip and shoulder harnesses are preferably cut from sheet plastic material—such a polypropylene—that is at least one millimeter thick and is substantially inextensible under the loads encountered in backpacks. Such plates are easily flexed in directions orthogonal to their planes but strongly resist coplanar flexing forces. As already indicated, the plates may be confined within a closely fitting textile cover that extends over the edges of the plate and/or edge bound with textile material to reduce chafing of an by their edges.

BRIEF DESCRIPTION OF THE DRAWINGS

Having broadly portrayed the nature of the present invention, a particular example will now be described with reference to the accompanying drawings. However, those skilled in the art will appreciate that many variations and modifications can be made to the example without departing from the scope of the invention as defined by the claims appended hereto. In the accompanying drawings:

FIG. 1, is a front elevation of the backpack of the chosen example, showing the hip harness and shoulder harness ready for use.

FIG. 2 is a front elevation of the backpack of FIG. 1 showing the hip harness segments in their stowed positions and a cover flap ready for deployment thereover.

FIG. 3 is a front elevation of the backpack of FIG. 1 showing the cover flap deployed and the backpack ready for transport.

FIG. 4 is an enlarged front elevation of the lower portion of the backpack of FIG. 1 showing the hip-plates, portions of their respective pivot joints and the attached buckle means.

FIG. 5 is a similar view to FIG. 4, with the hip-plates and buckle means removed, the outline of the frame elements being shown in broken lines.

FIG. 6 is a sectional side elevation of the right segment of the hip harness of FIG. 1 taken on section plane VI-VI of FIG. 1.

FIG. 7 is a rear elevation of the right hip harness segment and buckle means of FIG. 1, showing an optional stabilizing strap.

FIG. 8 is a similar view to FIG. 7 showing the right hip-plate of the right hip harness segment with the associated hip pad removed, showing the optional stabilizing strap illustrated in FIG. 7 together with a second stabilizing strap.

FIG. 9 is an enlarged front elevation of portion of one of the shoulder strap assemblies of FIG. 10 showing a contour plate fitted within its pocket.

FIG. 10 is a plan view of the shoulder harness removed from the backpack of FIG. 1 and laid out flat on a horizontal surface with its front uppermost and with three pairs of contour plates of different shapes that can be fitted within the pockets of the shoulder straps.

DETAILED DESCRIPTION

With reference to FIG. 1, the backpack 10 of the chosen example has a load-bag 12, a Y-shape shoulder harness 14, having left and right padded shoulder strap assemblies 14 a and 14 b and a common tail 16 that is adjustably secured to the base 18 of the pack by an anchor buckle 19, and a hip harness 20 comprised of (i) separate left and right side segments 20 a and 20 b pivotally attached to pack 10 near base 18 and (ii) waist buckle means 22. The front faces of segments 20 a and 20 b are covered by pads 64 a and 64 b (respectively, which will be described below. An optional lumbar flap 23 may be used to cover buckle 19 and shoulder harness tail 16 when the pack is worn. One end of flap 23 is sewn to base 18 so that the opposite end can be raised and attached by mating Velcro™ patches 23 a and 23 b to the front of pack 10.

Each strap assembly 14 a and 14 b of shoulder harness 14 essentially comprises (i) an elongated padded body 24 arranged to extend over the upper back and respective shoulder and down the respective side of the chest of the wearer, (ii) a load-bearing top-webbing 25 passing downward over the top front face of padded body 24, and (iii) a contour plate 26 fitted upwardly into a pocket 27 in the upper portion of body 24 that extends over the shoulder of the user. Each top-webbing 25 extends from a respective top anchor buckle 28 that is fixed to the load bag 12 a little below shoulder height. The lower end of each top-webbing 25 terminates at a respective bottom buckle 29 through which an adjustable bottom-webbing strap 30 is passed, one end of bottom-webbing 30 being anchored to base 18 of pack 10 and the other end hanging free to permit easy adjustment by pulling. Except for the use of contour plates 26 and their respective pockets 27 the general configuration and construction of the shoulder harness 14 is well known in the art.

FIG. 2 shows the pack with the side segments 20 a and 20 b of hip harness 20 swung up about their pivots (to be described below) to substantially vertical positions and lumbar flap 23 folded up and attached to the front of the pack in its normal position. A zip-around cover 32, which is attached to pack base 18 and is normally stowed in a zip-pocket 34 (see FIGS. 4 and 5) formed in the bottom 36 of load bag 12, is shown unpacked and extended from that pocket in FIG. 2. FIG. 3 shows cover 32 after it has been zipped in place, covering the entire harness system to ready pack 10 for transport.

FIG. 4 is an enlarged view of the lower portion of the front of pack 10 including the lumbar region, generally indicated by the bracket L. FIG. 4 shows the lower ends of padded bodies 24 of left and right shoulder strap assemblies 14 a and 14 b, the lower ends of top-webbings 25, bottom buckles 29 and bottom webbings 30. The tail 16 of the shoulder harness 14 and the anchor buckle 19 at the base 18 of pack 10 are also shown, along with zip pocket 34 for cover 32 in the bottom 36 of load bag 12, but the lumbar flap 23 is omitted for clarity. In FIG. 4, the left and right pads 64 a and 64 b of hip harness segments 20 a and 20 b shown in FIGS. 1 and 2 have been removed to show left and right flexible plastic hip-plate assemblies 37 a and 37 b that form part of the respective segments and will be described with reference to FIGS. 6, 7 and 8 below. Each hip-plate assembly comprises a sheet-plastic hip-plate 40 sewn into a tightly fitting strong fabric pocket 38 with edge bindings 39, plates 40 being shown in cut-away areas 41 of the fabric pockets 38. Hip-plate assemblies 37 a and 37 b have relatively narrow front ends 42, which are shown are shown flexed forwards and inwards and joined by waist buckle means 22 that comprises left and right belt-like webbing straps 44 a and 44 b joined by a central buckle 46. The rear ends of straps 44 a and 44 b are sewn directly to front ends 42 of respective hip-plate assemblies 37 a and 37 b. The relatively large rear or inner end portion 48 of each hip-plate assembly is lobe-like and located to oppose the respective gluteus maximus muscles of the wearer when pack 10 is in place. An eyelet 50 is swaged through each plate assembly 37 a and 37 b at approximately the center of the lobe of inner portion 48 so that the plate assembly can be pivotally secured to the frame of pack 10 by a countersunk-head screw 52 passing though eyelet 50, as will be described more particularly with reference to FIGS. 5 and 6. It is to be noted that the axes of screws 52 are substantially horizontal and parallel and extend generally in the front-to-back direction (when the pack is worn).

FIG. 5 is a similar view to that of FIG. 4 but with shoulder harness 14 and hip harness 20 removed, the latter being simply effected by first removing screws 52 (FIG. 4) leaving internally threaded nuts 54 in place. The exteriors of nuts 54 are cylindrical and extend through respective eyelets 55 that are swaged into the cloth facing 56 of the load bag 12 of pack 10. The lower ends of bottom webbings 30 of the shoulder harness 14 are anchored to the base of load bag 12 by being sewn between respective sides of facing 56 and the front of load bag 12.

In this example, the primary frame element is a lightweight, strong flat piece of plastic or aluminium, shown in outline by broken lines at 60 in FIG. 5 because it lies behind facing 56. In this example, primary frame element 60 is supplemented by left and right crossed strap-like secondary frame elements 61 a and 61 b respectively, which are preferably formed from aluminum sheet though plastic sheeting may also be used. Each secondary element extends diagonally upward to provide at their top ends (not shown) anchor points for (respectively) the right and left anchor buckles 28 (FIG. 1) of shoulder harness 14. Secondary frame elements 61 a and 61 b are also shown in broken lines as they also lie behind the facing 56 of load bag 12.

FIG. 6 is a sectional side elevation of right segment 20 b and portion of the front of load bag 12 taken on section plane VI-VI shown in FIG. 1, which passes through the right pivot joint formed (in part) by the right hand one of screws 52. It is to be noted that the sectional dimensions of the components shown in FIG. 6 have been exaggerated for the sake of clarity. Primary frame element 60 is located between cloth facing 56 (see FIG. 5) and a cloth backing 58 that form the font of load bag 12 and is held in position by the swaging of eyelet 55 through facing 56, frame element 60 and backing 58. In the example shown, nut 54 is swaged into the bottom end of the right secondary frame element 61 b and is of tubular form so that it extends forwards through the right eyelet 55 so as to positively locate the bottom end of secondary frame element 61 b with respect to primary frame element 60. Both secondary frame elements 61 a and 61 b are located within load bag 12 immediately behind backing cloth 58.

It might be noted that FIG. 6 also illustrates—in section—portion of the base 18 of pack 10 including zipped pocket 34 in the bottom 36 of and showing cover 32 packed into pocket 34.

Referring now to FIGS. 7 and 8 as well as to FIG. 6, right hip harness segment 20 b basically consists of right hip-plate assembly 37 b, (which includes plastic hip-plate 40 with sewn-on fabric cover 38 and edging 39, and with eyelet 50 swaged therethrough) and padded right boot 64 b fitted over the front of hip-plate assembly 37 b. Boot 64 b comprises a foam core 66 encased in a sewn fabric cover 68 having a rear pocket 70 accommodating lobe 48 of hip-plate 37 b and having a rear strap-like bridge 72 (FIG. 7) accommodating the narrow front portion 42 of hip-plate 37 b (along with the inner end of right strap 44 b of buckle means 22).

By way of review, it is to be noted that screws 52, nuts 54 and eyelets 50 and 55 serve to positively locate and assemble primary frame element 60, secondary frame elements 61, and left and right hip segments 20 a and 20 b together as a functioning assemblage. Primary frame element 60 thus serves to pivotally anchor the side segments 20 a and 20 b of hip harness 20, setting the relative location and spacing of left and right segments 20 a and 20 b and allowing buckle means 22 to be tightened without displacing the segments of the hip harness 20. A thread-locking compound can be used to prevent screws 52 working loose in nuts 54 during use.

It will be appreciated that there are many alternative arrangements by which the desired function of the side segments of the hip harness can be effected. A threaded nut can be carried by the primary frame element and a screw or bolt entered forwards from within the load bag of the pack. A tubular rivet that passes through all the components of the joint could be employed. Such a rivet could lock or clamp the primary and secondary frame elements together while allowing free-rotation of the hip-plate assemblies and their associated side segments. The secondary frame elements (if present, for they are optional) need not be fixed by the screw, rivet or the like that forms the pivot joint, but can be attached to the primary frame element elsewhere. Or the primary and secondary frame elements may form an integral cut or molded plastic structure that is entirely housed within the front face of the load bag.

FIGS. 4, 7 and 8 show an optional stabilizer link 80 that ties the lobe portions 48 of hip-plates assemblies 37 a and 37 b together so as to restrict their relative angular movement. Users with broad hips may find this helpful when carrying heavy loads so as to reduce the amount of load-shifting from one hip to the other while still permitting some pivotal movement of the hip harness. As shown in FIG. 4, link 80 comprises left and right straps 82 a and 82 b joined by a buckle 84 in such a way that the effective length of the link can be accurately adjusted, strap 82 a being sewn to the lobe of left hip-plate 37 a at a point below the pivot axis defined by the axis of screw 52 or eyelet 50 and strap 82 b being sewn to the lobe of right hip-plate 37 b in a corresponding location.

As an alternative or an addition to link 80, the narrow front portions 42 of hip-plates can be fitted with longer side stabilizer straps that attach to buckles at the base 18 of load bag 12 and on the same side. An example for the right side of the pack is shown a right side stabilizer strap 84 b on right hip-plate 37 b in FIG. 8. The free end of right side stabilizer strap 84 b attaches to right side buckle 85 b shown in FIG. 5. The left side stabilizer strap (not shown) attaches to left side buckle 85 a shown in FIG. 5. When heavy loads are carried the side stabilizer straps resist the tendency of buckle means 22 to rise; that is, they transfer some of the weight from the shoulders and buttocks to the hips.

The use of contour plates 26 and pockets 27 in the shoulder strap assemblies 14 a and 14 b will now be described with reference to FIGS. 9 and 10. FIG. 9 is an enlarged front perspective view of the portion of the left shoulder strap assembly 14 a that normally rests on the shoulder of the user. A guide to the orientation of this portion of shoulder strap assembly is provided by the broken line on the left of FIG. 9 indicating the front face of load bag 12. FIG. 10 is a plan view of shoulder harness 14 depicted as if lying on a horizontal surface and viewed from the back and top so that left and right shoulder strap assemblies 14 a and 14 b appear reversed with respect to FIG. 1. Most of the tension webbings 25 (see FIG. 1) have been cut away for clarity in FIGS. 9 and 10.

As already noted, left and right shoulder strap assemblies 14 a and 14 b have padded bodies 24. The padding is normally heaviest in the shoulder region where it rests against the tops of the shoulders and, sometimes, the pectoral muscles of the user, this heavy padding being indicated at 90 in the perspective view of the left strap assembly 14 a in FIG. 9 and in the front elevation of FIG. 1. As described with respect to FIG. 1, a pocket 27 is formed in the outer or upper lining of the shoulder portion of each strap assembly to take a selected contour plate 26, most of which is shown in broken lines in FIG. 9 because it is located within pocket 27. The purpose of contour plate 26 is to laterally shape the shoulder portions of the strap assemblies so as to make them more comfortable under load and so as to inhibit the bunching or curling of padded portion 90.

Because of the wide variation in shoulder, chest and breast size and shape between people and, in particular, between men and women, the optimum lateral curve of the shoulder portions of the strap assemblies will vary widely even for the same pack and load. It has been found that much of this variation can be accommodated by selecting between contour plates of different, shapes, stiffness and curvature for use in a common shoulder harness that has tight-fitting pockets shaped to take the plates. An added degree of accommodation is possible by varying the location of the pockets along the shoulder strap assemblies of the shoulder harness. This may be done by forming multiple pockets in the outer lining or by controlling the vertical location of a contour plate within a long pocket. In general, however, only one pocket over each shoulder will be sufficient as in the illustrative example.

FIG. 10 shows shoulder harness 14 of the pack of FIG. 1 laid out in the manner indicated above, with tension webbings 25 cut away and pockets 27 showing. Three alternative contour plates 26 d, 26 e and 26 f having increasing curvature are shown along side each pocket 27. Conveniently, the plates may be stamped or cut from plastic sheeting between 0.5 and 3 mm in thickness with the thicker plates having holes formed therein to reduce weight if desired. Plates 26 d are shown with holes 92 for this purpose. As in FIG. 10, the alternative plates may be relatively short and may all be of essentially the same width (though of differing curvature). As indicated in FIG. 9, they may be relatively long and of tapering form. If desired, the plates may be enclosed in a fabric pocket with the perimeter finished with a binding tape in a similar way to the reinforcing plates 40 of hip-plate assemblies 37 a and 37 b.

It is desirable that pockets 27 are formed with upper and lower layers of material securely sewn together on their sides and lower ends, each pocket then being secured to the padded portion of the corresponding strap assembly 14 a or 14 b. Thus, selected contour plate does not come into contact with the padding 90 of the strap and can be made a firm fit within pocket 27. The material of the upper and lower surfaces of the pocket 27, as well as adjacent material covering padded body 24, is preferably of woven construction and cut on the bias so as to facilitate conformity of this region the strap assembly to the shape of curved plates such as 26 f. The bias cut is indicated by hatching 96 in FIG. 9.

It will be appreciated by those skilled in the art that the backpack of the chosen example offers many advantages over known backpacks in the comfortable distribution of the load between the shoulders and the hips, this being achieved in important part by the use of the contour plates in the shoulder harness and the reinforcing plates of the hip harness. Important and separate advantages are also obtained from the use of independently pivoted hip harness segments. However, those skilled in the art will also appreciate that many variations and additions can be made to the backpack of the example without departing from the scope of the invention as defined by the following claims. 

1. A backpack having a lumbar portion that is opposed to the lumbar region of the user's back when the pack is worn, the backpack including: a shoulder harness adapted to transfer some weight of the backpack to the shoulders of the user when the backpack is worn, a hip harness adapted to encircle the waist of the user and to transfer some of weight of the backpack to the gluteal muscles and hips of the user when the backpack is worn, a primary frame element located within said lumbar portion, and pivot joint means securing the hip harness to the frame element to enable lateral pivoting movement of the hip harness with respect to the frame element and to the remainder of the backpack.
 2. A backpack according to claim 1 wherein: said hip harness comprises: a left segment having a rear portion located between the lumbar region of the user's back and said frame element when the pack is worn, a right segment having a rear portion located between the lumbar region of the user's back and said frame element when the pack is worn, and said pivot joint means secures said rear portions of said left and right segment to the primary frame element to enable independent lateral pivoting movement of each segment with respect to the frame element.
 3. A backpack according to claim 2 wherein: said rear portion of the said left segment is located to the left of the spine of a user wearing the backpack, said rear portion of the said right segment is located to the right of the spine of a user wearing the backpack, said pivotal joint means comprises: a left pivot joint securing the rear portion of the left segment to the frame element for pivotal movement about a left pivot axis, and a right pivot joint securing the rear portion of the right segment to the frame element for pivotal movement about a right pivot axis, and wherein said left pivot axis is spaced horizontally from said right pivot axis, and said left and right segments of the hip harness are capable of independent pivotal movement about their respective pivot axes.
 4. A backpack according to claim 3 wherein, when the back pack is worn by an upright user: said rear portion of the left hip segment is adapted for location over at least portion of the user's left gluteus maximus muscle, and said rear portion of the right hip segment is adapted for location over at least portion of the user's right gluteus maximus muscle.
 5. A backpack according to claim 3 wherein: the left segment of the hip harness includes an elongate flexible and substantially inextensible left hip-plate, said left hip-plate having a rear portion that is attached by said left pivot joint to the frame element and said left hip-plate having a front portion, the right segment of the hip harness includes an elongate flexible and substantially inextensible right hip-plate, said right hip-plate having a rear portion that is attached by said right pivot joint to the frame element and said right hip-plate having a front portion, and and the hip harness includes buckle means adapted to connect said front portion of said left hip-plate to said front portion of said right hip-plate across the abdomen of a user wearing the backpack.
 6. A backpack according to claim 5 wherein: said rear portion the left hip-plate is coupled to said rear portion of the right hip-plate by stabilizer strap means located below the level of said left and said right pivot joints, said stabilizer strap means is operable to limit the degree to which the front portions of the left and right hip-plates can be jointly raised, and said stabilizer strap means includes a releasable buckle so that, upon release of said releasable buckle the degree to which the front portions of the left and right hip-plates can be raise is not limited by the stabilizer strap means.
 7. A backpack according to claim 5 wherein: a left stabilizer strap having a front end and a rear end is attached by said front end to the front portion the left hip-plate, left attachment means for the rear end of said left stabilizer strap is provided on the left side of the load bag at a level below said left pivot joint, so that by attaching the rear end of the left stabilizer strap to the said left attachment means and by adjusting the length the left stabilizer strap, the degree to which the front portion of the left hip-plate can be raised is limited by the left stabilizer strap, a right stabilizer strap having a front end and a rear end is attached by said front end to the front portion the right hip-plate, right attachment means for the rear end of said right stabilizer strap is provided on the rigtht side of the load bag at a level below said right pivot joint, so that by attaching the rear end of the right stabilizer strap to the said right attachment means and by adjusting the length the right stabilizer strap, the degree to which the front portion of the right hip-plate can be raised is limited by the right stabilizer strap.
 8. A backpack according to claim 5 wherein: a left padded boot is fitted around the rear portion of the left hip-plate so that said boot is interposed between the rear portion of the left hip-plate and the user when the backpack is worn, said rear portion of the left hip-plate and said left padded boot comprising said the rear portion of the left hip-segment, and a right padded boot is fitted around the rear portion of the right hip-plate so that said right padded boot is interposed between the rear portion of the right hip-plate and the user when the backpack is worn, said rear portion of the right hip-plate and said right padded boot comprising said the rear portion of the right hip-segment,
 9. A backpack according to claim 3 wherein: said left and right hip-segments can each be pivoted to a substantially vertical position when the backpack is upright but is not being worn, and a zip-around cover is removably incorporated in the backpack and adapted to be withdrawn over said segments when each is pivoted to said vertical position and zipped therearound to enclose the entire hip harness between the cover and the body of the backpack.
 10. A backpack according to claim 5 wherein: the left pivot joint comprises a left eyelet fitted into said left hip-plate and a left screw that passes through said left eyelet and enters said frame element, the right pivot joint comprises a right eyelet fitted into said right hip-plate and a right screw that passes through said right eyelet and enters said frame element, and said left and right screws are arranged so as to extend generally horizontally in a front-to-back direction when the backpack is worn by an upright user.
 11. A backpack according to claim 5 wherein: the backpack includes a load bag having a front face that is opposed to the back of a user when the pack is worn, the shoulder harness includes left and right shoulder strap assemblies supported from respective anchor buckles attached to said front face near the respective shoulder of the user, when the backpack is worn, said primary frame element comprises a substantially inextensible laterally extending plate located within or against said front face of the load bag, and there is at least one secondary frame element comprising a vertically extending substantially inextensible plate located within or against the front face of the load bag, said secondary frame element or frame elements mechanically connecting said primary frame element to said anchor points for said shoulder strap assemblies.
 12. A backpack according to claim 11 wherein: there are two second secondary elongate frame elements comprising a left secondary frame element having an upper end and a lower end and a right secondary frame element having an upper and a lower end, the lower end of said left secondary frame element is attached to said left pivot joint, the lower end of said right secondary frame element is attached to said right pivot joint, the upper end of said left secondary frame element is attached to one of said anchor buckles, and the upper end of said right secondary frame element is attached to the other one of said anchor buckles.
 13. A backpack according to claim 3 wherein said shoulder harness comprises: flexible left and right shoulder strap assemblies, each assembly including an elongate portion that extends from the respective shoulder and over the respective pectoral area of a user wearing the pack, an elongate pocket is formed in said elongate portion of each shoulder strap, an elongate contour plate is fitted into each of said pockets, said contour plate being longitudinally flexible but laterally stiff, and the lateral shape of said portion of each shoulder strap assembly is at least partially determined by the shape of said contour plates fitted in the respective one of said pockets.
 14. A backpack comprising: flexible left and right shoulder strap assemblies, each assembly including an elongate portion that extends from the respective shoulder and over the respective pectoral area of a user wearing the pack, an elongate pocket is formed in said portion of each shoulder strap assembly, an elongate contour plate is fitted into each of said pockets, said contour plate being longitudinally flexible but laterally stiff, and wherein the lateral shape of each of said portions of the shoulder strap assemblies is at least partially determined by the lateral shape of the respective contour plates fitted in the respective pockets of the shoulder strap assembly.
 15. A backpack according to claim 5, wherein: at least one of said plates is formed from stitchable sheet plastic that is at least one millimeter thick and can be readily flexed in directions orthogonal to the plane of the plate while being stiff and resistant to bending in the plane of the plate, said at least one plate having a peripheral edge, said peripheral edge is covered by a cloth edging stitched thereto, thereby mitigating the danger of wear to other components of the backpack caused by rubbing against said peripheral edge. 